Intestinal cell damage and systemic immune activation in individuals reporting sensitivity to wheat in the absence of coeliac disease

Effective Degradation of Gluten and Its Fragments by Gluten-Specific Peptidases: A Review on Application for the Treatment of Patients with Gluten Sensitivity

To date, there is no effective treatment for celiac disease (CD, gluten enteropathy), an autoimmune disease caused by gluten-containing food. Celiac patients are supported by a strict gluten-free diet (GFD). However, in some cases GFD does not negate gluten-induced symptoms. Many patients with CD, despite following such a diet, retain symptoms of active disease due to high sensitivity even to traces of gluten. In addition, strict adherence to GFD reduces the quality of life of patients, as often it is difficult to maintain in a professional or social environment. Various pharmacological treatments are being developed to complement GFD. One promising treatment is enzyme therapy, involving the intake of peptidases with food to digest immunogenic gluten peptides that are resistant to hydrolysis due to a high prevalence of proline and glutamine amino acids. This narrative review considers the features of the main proline/glutamine-rich proteins of cereals and the conditions that cause the symptoms of CD. In addition, we evaluate information about peptidases from various sources that can effectively break down these proteins and their immunogenic peptides, and analyze data on their activity and preliminary clinical trials. Thus far, the data suggest that enzyme therapy alone is not sufficient for the treatment of CD but can be used as a pharmacological supplement to GFD.

Evaluation of parameters associated with growth retardation in children with coeliac disease

AIMS

Coeliac disease (CD) is an autoimmune disorder with a prevalence ≤2% that causes an immune reaction to gluten. Growth retardation (GR) generally accompanies CD due to gastrointestinal complications and should be treated as early as possible along with initiation of a gluten-free diet. The aim of this study was to determine the indicators of GR in patients with CD.

METHODS

This single-centre retrospective study included paediatric outpatients with CD. All patients were diagnosed with CD via serological analysis and upper gastrointestinal endoscopy if necessary. Patient records were obtained from Adana City Training and Research Hospital. Patients that were diagnosed with GR accompanying CD were given oral nutritional supplements and followed-up every 3-6 months. Statistical relationships between demographics, and anthropometric measurements, duration of breastfeeding, gluten contact time, diet duration, presenting complaints and serological findings were evaluated.

RESULTS

This study included 169 paediatric outpatients between ages 1 and 18. Longer symptom duration and shorter breastfeeding duration were significantly correlated with GR accompanying CD (P = 0.007 and P = 0.029, respectively). Vomiting was the only symptom that was correlated with the presence of GR (P = 0.010). Helicobacter pylori infection was not correlated with the presence of GR (P = 0.277).

CONCLUSIONS

GR should be treated as early as possible to reduce the severity of CD and a 6 months sole breastfeeding followed by solid foods accompanied by breastfeeding for 2 years is crucial for preventing GR. Moreover, vomiting as a presenting complaint in patients with CD might be indicative of the presence of GR.

Associations Between Subclass Profile of IgG Response to Gluten and the Gastrointestinal and Motor Symptoms in Children With Cerebral Palsy

OBJECTIVE

Gastrointestinal problems are often seen in children with cerebral palsy, although the etiology and underlying mechanisms are not fully understood. Recent data point to significantly elevated levels of IgG antibody to dietary gluten in cerebral palsy independent of celiac disease, a gluten-mediated autoimmune enteropathy. We aimed to further characterize this antibody response by examining its subclass distribution and target reactivity in the context of relevant patient symptom profile.

METHODS

Study participants included children with cerebral palsy (n = 70) and celiac disease (n = 85), as well as unaffected controls (n = 30). Serum IgG antibody to gluten was investigated for subclass distribution, pattern of reactivity towards target proteins, and relationship with gastrointestinal symptoms and motor function.

RESULTS

The anti-gluten IgG antibody response in the cerebral palsy cohort was constituted of all 4 subclasses. In comparison with celiac disease, however, IgG1, IgG2, and IgG3 subclasses were significantly lower, whereas the IgG4 response was significantly higher in cerebral palsy. Within the cohort of cerebral palsy patients, levels of anti-gluten IgG1, IgG3, and IgG4 were greater in those with gastrointestinal symptoms, and the IgG3 subclass antibody correlated inversely with gross motor function. The anti-gluten IgG antibodies targeted a broad range of gliadin and glutenin proteins.

CONCLUSIONS

These findings reveal an anti-gluten IgG subclass distribution in cerebral palsy that is significantly different from that in celiac disease. Furthermore, the observed association between IgG subclass and symptom profile is suggestive of a relationship between the immune response and disease pathophysiology that may indicate a role for defects in gut immune and barrier function in cerebral palsy.

Maternal antibodies to gliadin and autism spectrum disorders in offspring-A population-based case-control study in Sweden

While individuals diagnosed with autism spectrum disorders (ASD) have higher levels of antibodies directed towards gliadin, a component of wheat gluten, no study has examined anti-gliadin antibodies (AGA) in etiologically relevant periods before diagnosis. The objective of this study was to investigate if maternal levels of AGA, during pregnancy and at the time of birth, are associated with ASD in offspring. We analyzed AGA in archived neonatal dried blood spots (NDBS) for 921 ASD cases and 1090 controls, and in paired maternal sera collected earlier in pregnancy for a subset of 547 cases and 428 controls. We examined associations with ASD diagnoses as a group and considering common comorbidities (intellectual disability [ID] and attention-deficit/hyperactivity disorder). We compared 206 cases to their unaffected siblings to examine the potential for confounding by shared familial factors. Odds of ASD tended to be lower among those with the highest levels (≥90th percentile) of AGA compared to those with low levels (<80th percentile; OR 0.78, 95% CI 0.56-1.09, measured in NDBS). This pattern was more apparent for ASD with comorbid ID when measured in NDBS (0.51, 0.30-0.87), with a similar trend in maternal sera (0.55, 0.24-1.29). High levels of AGA were similarly associated with lower odds of ASD in the sibling comparison. In summary, we found little association between maternal antibodies raised against components of gluten and risk of ASD in general. Exposure to high levels of AGA in the pre- and perinatal periods may be protective in terms of risk for ASD with ID. LAY SUMMARY: There is a debate among both scientists and community members as to whether an immune reaction to gluten exposure could be considered a cause of autism. We examined antibodies that are directed against gliadin, a part of gluten, in samples collected from pregnant mothers and their newborn babies. We did not see any major differences in the antibody level among those children diagnosed with ASD or their mothers compared to children who were not diagnosed with ASD. High levels of the antibodies were in fact associated with a somewhat lower risk of ASD with co-occurring intellectual disabilities, though we cannot tell from this study why that might be the case.

Identification of leaky gut-related markers as indicators of metabolic health in Dutch adults: The Nutrition Questionnaires plus (NQplus) study

Background and aim

Chronic inflammation is a primary risk factor for chronic metabolic disease and may be triggered by a “leaky gut.” Several biomarkers have been recognized to indicate intestinal permeability (i.e., leaky gut) and bacterial translocation. Nonetheless, which of these biomarkers exhibit the highest correlation with metabolic health parameters remains unclear. Hence, this study aimed to explore the correlation between leaky gut-related markers and metabolic health.

Methods

Based on waist circumference, plasma fasting glucose, plasma gamma-glutamyl transpeptidase (GGT), and plasma LDL cholesterol, two groups of 40 subjects with the most extreme metabolic health profiles were selected from the NQplus cohort study (n = 2048), which was previously conducted by the Wageningen University’s Division of Human Nutrition. Eight potential leaky gut-related markers were selected from the literature and measured in serum or EDTA plasma samples of these selected individuals. These samples were also obtained from the NQplus cohort study.

Results

From the leaky gut markers, levels of zonulin, lipopolysaccharide-binding protein, soluble CD14, bactericidal/permeability-increasing protein, and peptidoglycan were significantly higher in individuals with unhealthy metabolic profiles (p<0.05). No differences in EndoCAb IgM, EndoCAb IgA, and EndoCAb IgG were observed between healthy and unhealthy individuals. Stepwise regression analysis revealed that zonulin was substantially associated with metabolic health parameters such as BMI, blood glucose, triglyceride, GGT, and C-reactive protein levels. C-reactive protein, an inflammation marker, showed the most pronounced association with zonulin.

Conclusions

Biomarkers that link a leaky gut and subsequent bacterial translocation to metabolic health were identified in this study. Especially zonulin may aid in monitoring a leaky gut and detecting individuals at risk for developing chronic metabolic diseases.

Tritordeum breads are well tolerated with preference over gluten-free breads in non-celiac wheat-sensitive patients and its consumption induce changes in gut bacteria

BACKGROUND

The ingestion of wheat and other cereals are related to several gut disorders. The specific components responsible for non-celiac wheat-sensitivity (NCWS) may include gluten and other compounds. Tritordeum is a new cereal derived from crossing durum wheat with a wild barley species, which differs from bread wheat in its gluten composition. In the present work, we examined the response of NCWS patients to tritordeum bread Gastrointestinal symptoms as well as tritordeum acceptability, gluten immunogenic peptides excretion, and the composition and structure of the intestinal microbiota were evaluated.

RESULTS

Gastrointestinal symptoms of the subjects showed no significant change between the gluten-free bread and the tritordeum bread. Participating subjects rated tritordeum bread higher than the gluten-free bread. Analysis of the bacterial gut microbiota indicated that tritordeum consumption does not alter the global structure and composition of the intestinal microbiota, and only a few changes in some butyrate-producing bacteria were observed.

CONCLUSIONS

All the results derived from acceptability, biochemical and microbiological tests suggest that tritordeum may be tolerated by a sub-set of NCWS sufferers who do not require strict exclusion of gluten from their diet. © 2020 Society of Chemical Industry.

Non-Celiac Gluten Sensitivity: An Update

Non-celiac gluten sensitivity (NCGS) is a clinical entity characterized by the absence of celiac disease and wheat allergy in patients that trigger reproducible symptomatic responses to gluten-containing foods consumption. Due to the lack of sensitive and reproducible biomarkers for NCGS diagnosis, placebo-controlled gluten challenges must be carried out for its diagnosis. The gluten challenges can be either double- or single-blind, for research or clinical practice purposes, respectively. For improving our understanding about the magnitude and relevance of NCGS in different populations, epidemiological studies based on self-report have been carried out. However, the gluten challenge-based prevalence of NCGS remains to be estimated. Since NCGS was recently recognized as a clinical entity, more studies are needed to delve into NCGS pathogenesis, for instance, the molecular interactions between the suspected cereal grain components that trigger NCGS, such as fermentable oligo-, di-, monosaccharides, and polyols (FODMAPs) and amylase and trypsin inhibitors, and the immune system remains to be elucidated. Although still under debate, NCGS patients can be susceptible to only one or more than one of the NCGS triggers. The treatment of NCGS involves the dietary restriction of the suspected triggers of the disease, but there is controversial data about the effectiveness of different dietary interventions such as the gluten-free diet and low-FODMAP diet. Certainly, our understanding of NCGS is improving quickly due to the constant availability of new scientific information on this topic. Thus, the aim of the present narrative review is to present an up-to-date overview on NCGS from epidemiology to current therapy.

Autoimmunity Features in Patients With Non-Celiac Wheat Sensitivity

INTRODUCTION

Nonceliac wheat sensitivity (NCWS) is characterized by intestinal and extraintestinal manifestations consequent to wheat ingestion in subjects without celiac disease and wheat allergy. Few studies investigated the relationship between NCWS and autoimmunity. The aim of this study is to evaluate the frequency of autoimmune diseases (ADs) and autoantibodies in patients with NCWS.

METHODS

Ninety-one patients (13 men and 78 women; mean age of 40.9 years) with NCWS, recruited in a single center, were included. Seventy-six healthy blood donors (HBD) and 55 patients with a diagnosis of irritable bowel syndrome (IBS) unrelated to NCWS served as controls. Autoantibodies levels were measured. Human leukocyte antigen haplotypes were determined, and duodenal histology performed in all patients carrying the DQ2/DQ8 haplotypes. Participants completed a questionnaire, and their medical records were reviewed to identify those with ADs.

RESULTS

Twenty-three patients with NCWS (25.3%) presented with ADs; autoimmune thyroiditis (16 patients, 17.6%) was the most frequent. The frequency of ADs was higher in patients with NCWS than in HBD (P = 0.002) and in patients with IBS (P = 0.05). In the NCWS group, antinuclear antibodies tested positive in 71.4% vs HBD 19.7%, and vs patients with IBS 21.8% (P < 0.0001 for both). The frequency of extractable nuclear antigen antibody (ENA) positivity was significantly higher in patients with NCWS (21.9%) than in HBD (0%) and patients with IBS (3.6%) (P = 0.0001 and P = 0.004, respectively). Among the patients with NCWS, 9.9% tested positive for antithyroglobulin, 16.5% for antithyroid peroxidase, and 14.3% for antiparietal cell antibodies; frequencies were not statistically different from controls. The presence of ADs was related to older age at NCWS diagnosis, female sex, duodenal lymphocytosis, and eosinophil infiltration.

DISCUSSION

One in 4 patients with NCWS suffered from AD, and serum antinuclear antibodies were positive in a very high percentage of cases. These data led us to consider NCWS to be associated to ADs.

A Riddle, Wrapped in a Mystery, Inside an Enigma: Another Key to Wheat Sensitivity?

Nonceliac gluten sensitivity, or the more preferred term, nonceliac wheat sensitivity (NCWS), is a heterogenous condition that is diagnosed purely on the basis of symptoms and without an understanding of disease mechanisms and triggers. Biomarkers to identify patients and implementation of dietary treatment in a personalized manner are needed. Mansueto et al. identified a population of NCWS patients with associated autoimmune markers and immune activation. The presence of these markers could be used, in combination with other serological tests, to help develop better diagnostic strategies for NCWS.

Non-Celiac Gluten/Wheat Sensitivity: Clinical Characteristics and Microbiota and Mycobiota Composition by Response to the Gluten Challenge Test

The aims of this observational “proof-of-concept” study were to analyze the clinical/psychological characteristics and gut microbiota/mycobiota composition of individuals with suspected non-celiac gluten/wheat sensitivity (NCGS/WS) according to responses to the double-blind-placebo-controlled (DBPC) crossover gluten challenge test. Fifty individuals with suspected NCGS/WS were subjected to the DBPC challenge test; anthropometric measurements, psychometric questionnaires, and fecal samples were collected. Twenty-seven (54%) participants were gluten responsive (NCGS), and 23 were placebo responsive, with an order effect. NCGS individuals displayed a significantly lower risk of eating disorders and a higher mental health score when compared to placebo-responsive participants, confirmed by multiple logistic regression analyses (OR = 0.87; 95% CI 0.76–0.98, p = 0.021, and OR = 1.30; 95% CI 1.06–1.59, p = 0.009, respectively). Principal coordinate analyses based on microbiota composition showed a separation by the DBPC response (p = 0.039). For Bacteroides (p = 0.05) and Parabacteroides (p = 0.007), the frequency of amplicon sequence variants was lower, and that for Blautia (p = 0.009) and Streptococcus (p = 0.004) was higher in NCGS individuals at multiple regression analyses. No difference in the mycobiota composition was detected between the groups. In conclusion, almost half of the individuals with suspected gluten sensitivity reported symptoms with placebo; they showed lower mental health scores, increased risk for eating disorders, and a different gut microbiota composition.

Gut epithelial impairment, microbial translocation and immune system activation in inflammatory bowel disease-associated spondyloarthritis

OBJECTIVES

Gut microbiota has been widely reported to be involved in systemic inflammation through microbial translocation and T cell activation in several diseases. In this work we aimed to investigate bacterial infiltration and epithelial impairment in the gut of patients with IBD-associated SpA (SpA-IBD), as well as the relationship of microbial translocation with immune system activation and their putative role in the pathogenesis of joint inflammation in IBD patients.

METHODS

Tight-junction proteins (TJPs) occludin and claudin-1/-4 and bacteria were assessed by real-time PCR analysis and immunohistochemical staining of the ileum. Intestinal fatty acid binding protein (I-FABP), lipopolysaccharides (LPS), soluble CD14 (sCD14), sclerostin and anti-sclerostin antibodies (anti-sclerostin-IgG) were assayed with ELISAs and peripheral mononuclear blood cells with flow cytometry. LPS and sCD14 were used in vitro to stimulate a human osteoblast cell line.

RESULTS

Compared with IBD, ileal samples from SpA-IBD patients showed bacterial infiltration, epithelial damage and downregulation of TJPs. In sera, they showed higher serum levels of I-FABP, LPS, sCD14 (the latter correlating with sclerostin and anti-sclerostin-IgG) and higher CD80+/CD163+ and lower CD14+ mononuclear cells. In vitro experiments demonstrated that only the LPS and sCD14 synergic action downregulates sclerostin expression in osteoblast cells.

CONCLUSION

SpA-IBD patients are characterized by gut epithelium impairment with consequent translocation of microbial products into the bloodstream, immune system activation and an increase of specific soluble biomarkers. These findings suggest that gut dysbiosis could be involved in the pathogenesis of SpA-IBD and it could hopefully prompt the use of these biomarkers in the follow-up and management of IBD patients.

An algorithm for differentiating food antigen-related gastrointestinal symptoms

AIM

The aim of this clinical audit was to assess patient-reported outcomes on the effect of dietary intervention, to enhance our understanding of possible treatment options in irritable bowel syndrome (IBS).

BACKGROUND

A large number of food-related gastro-intestinal disorders have been attributed to IBS for decades.

METHODS

Patient-reported outcomes from the records of 149 IBS patients treated at secondary and tertiary Gastroenterology outpatients in two UK hospitals between January 2014 and July 2016 were audited. Patients all presented with symptoms fulfilling Rome III-IV criteria for IBS had negative coeliac serology and did not have other gastrointestinal (GI) conditions. A modified version of a low FODMAP diet had been recommended (gluten and lactose free diet (G/LFD)) and was implemented for 6 weeks. Outcomes and dietary adherence were recorded during outpatient's consultations.

RESULTS

A total of 134 patients complied with the diet optimally. The majority had an improvement rate >70% and continued with the diet. Fifty-three percent became completely or almost asymptomatic, while 27.6% had a poor response to the diet (scoring < 30%) to G/LFD. The improvement was excellent in patients with normal BMI and good in overweight and obese and where BMI <18. Over 50% did not require any follow-up within 12 months.

CONCLUSION

Although it is unclear whether symptoms are triggered by gluten, fructans or lactose, elimination of gluten and lactose proved to be an effective treatment in patients with IBS. Multidisciplinary team management and implementation of detailed nutrition therapy using the audit algorithm might prove to be both cost effective and efficacious a treatment option in IBS.

Pro-Inflammatory Effect of Gliadins and Glutenins Extracted from Different Wheat Cultivars on an In Vitro 3D Intestinal Epithelium Model

There is a need to assess the relationship between improved rheological properties and the immunogenic potential of wheat proteins. The present study aimed to investigate the in vitro effects of total protein extracts from three modern and two landrace Triticum aestivum commercial flour mixes, with significant differences in gluten strength (GS), on cell lines. Cytotoxicity and innate immune responses induced by wheat proteins were investigated using Caco-2 monocultures, two dimensional (2D) Caco-2/U937 co-cultures, and three dimensional (3D) co-cultures simulating the intestinal mucosa with Caco-2 epithelial cells situated above an extra-cellular matrix containing U937 monocytes and L929 fibroblasts. Modern wheat proteins, with increased GS, significantly reduced Caco-2 cell proliferation and vitality in monoculture and 2D co-cultures than landrace proteins. Modern wheat proteins also augmented Caco-2 monolayer disruption and tight junction protein, occludin, redistribution in 3D co-cultures. Release of interleukin-8 into the cell medium and increased U937 monocyte migration in both 2D and 3D co-cultures were similarly apparent. Immuno-activation of migrating U937 cells was evidenced from cluster of differentiation 14 (CD14) staining and CD11b-related differentiation into macrophages. The modern wheat proteins, with gluten polymorphism relatedness and increased GS, were shown to be more cytotoxic and immunogenic than the landrace wheat proteins.

Is Gluten the Only Culprit for Non-Celiac Gluten/Wheat Sensitivity?

The gluten-free diet (GFD) has gained increasing popularity in recent years, supported by marketing campaigns, media messages and social networks. Nevertheless, real knowledge of gluten and GF-related implications for health is still poor among the general population. The GFD has also been suggested for non-celiac gluten/wheat sensitivity (NCG/WS), a clinical entity characterized by intestinal and extraintestinal symptoms induced by gluten ingestion in the absence of celiac disease (CD) or wheat allergy (WA). NCG/WS should be regarded as an "umbrella term" including a variety of different conditions where gluten is likely not the only factor responsible for triggering symptoms. Other compounds aside from gluten may be involved in the pathogenesis of NCG/WS. These include fructans, which are part of fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs), amylase trypsin inhibitors (ATIs), wheat germ agglutinin (WGA) and glyphosate. The GFD might be an appropriate dietary approach for patients with self-reported gluten/wheat-dependent symptoms. A low-FODMAP diet (LFD) should be the first dietary option for patients referring symptoms more related to FODMAPs than gluten/wheat and the second-line treatment for those with self-reported gluten/wheat-related symptoms not responding to the GFD. A personalized approach, regular follow-up and the help of a skilled dietician are mandatory.

Non-Celiac Gluten Sensitivity in the Context of Functional Gastrointestinal Disorders

Gluten-free diets are increasingly chosen in the Western world, even in the absence of a diagnosis of celiac disease. Around 10% of people worldwide self-report gluten-related complaints, including intestinal and extra-intestinal symptoms. In most cases, these subjects would be labeled as patients suffering from irritable bowel syndrome (IBS) who place themselves on a gluten-free diet even in the absence of celiac disease. In some instances, patients report a clear benefit by avoiding gluten from their diet and/or symptom worsening upon gluten reintroduction. This clinical entity has been termed non-celiac gluten sensitivity (NCGS). The symptoms referred by these patients are both intestinal and extra-intestinal, suggesting that similarly to functional gastrointestinal disorders, NCGS is a disorder of gut-brain interaction. It remains unclear if gluten is the only wheat component involved in NCGS. The mechanisms underlying symptom generation in NCGS remain to be fully clarified, although in the past few years, the research has significantly moved forward with new data linking NCGS to changes in gut motility, permeability and innate immunity. The diagnosis is largely based on the self-reported reaction to gluten by the patient, as there are no available biomarkers, and confirmatory double-blind challenge protocols are unfeasible in daily clinical practice. Some studies suggest that a small proportion of patients with IBS have an intolerance to gluten. However, the benefits of gluten-free or low-gluten diets in non-celiac disease-related conditions are limited, and the long-term consequences of this practice may include nutritional and gut microbiota unbalance. Here, we summarize the role of gluten in the clinical features, pathophysiology, and management of NCGS and disorders of gut-brain interaction.

Endotoxemia coupled with heightened inflammation predicts future depressive symptoms

OBJECTIVE

Cross-sectional data have linked gut barrier abnormalities and endotoxemia with depression, even among those without gastrointestinal symptoms. This study examined longitudinal associations between endotoxemia markers and depressive symptoms, as well as the role of inflammation in this relationship.

DESIGN

At three annual visits, 315 women (n=209 breast cancer survivors, n = 106 non-cancer patient controls, M=55 years old) completed the Center for Epidemiological Studies Depression questionnaire (CES-D) and provided blood samples to assess inflammatory markers - interleukin-6, tumor necrosis factor-alpha, and C-reactive protein - and endotoxemia markers - lipopolysaccharide-binding protein (LBP), soluble CD14 (sCD14), and their ratio.

RESULTS

Adjusting for key demographic variables, health behaviors, visit 1 depressive symptoms, and cancer status and treatment, women with higher visit 1 LBP and LBP/sCD14 had more depressive symptoms at the two subsequent annual visits. Illustrating the notable impact, a woman at the 75th percentile for LBP or LBP/sCD14 at visit 1 was 18 % more likely to report clinically significant depressive symptoms (CES-D ≥16) at follow-up than a woman in the lowest quartile. Cancer status and treatment type did not modulate this relationship. In contrast, visit 1 depressive symptoms did not predict endotoxemia at follow-up. A significant interaction between LBP/sCD14 and inflammatory burden suggested that visit 1 endotoxemia fueled depressive symptoms only in the context of elevated inflammation.

CONCLUSION

These results suggest that endotoxemia, combined with systemic inflammation, can drive depressive symptoms. These findings may implicate bacterial endotoxin translocation from the gut to the bloodstream in depression etiology. Interventions that reduce endotoxemia and inflammation may lessen the risk of depression.

Serum zonulin and its diagnostic performance in non-coeliac gluten sensitivity

OBJECTIVE

Non-coeliac gluten sensitivity (NCGS) is characterised by intestinal and extraintestinal symptoms related to the ingestion of gluten-containing foods, in the absence of coeliac disease (CD) and wheat allergy. No biomarkers are available to diagnose NCGS and the gold standard double-blind placebo-controlled gluten challenge is clinically impractical. The aim of our work was to investigate the role of serum zonulin as a diagnostic biomarker of NCGS and to develop a diagnostic algorithm.

DESIGN

In a multicentre study, we enrolled 86 patients with either self-reported or double-blind confirmed NCGS, 59 patients with diarrhoea-predominant IBS (IBS-D), 15 patients with CD and 25 asymptomatic controls (AC). Zonulin serum levels were assessed and the associated diagnostic power calculated. Clinical and symptomatic data were recorded. The effect of diet on zonulin levels was evaluated in a subgroup of patients with NCGS.

RESULTS

Compared with ACs, the NCGS, irrespective of modality of diagnosis, and patients with CD had significantly increased levels of zonulin, as did both NCGS and patients with CD compared with participants with IBS-D. Self-reported NCGS showed increased zonulin levels compared with double-blind confirmed and not-confirmed NCGS. Six-month wheat avoidance significantly reduced zonulin levels only in HLA-DQ2/8-positive participants with NCGS. The diagnostic accuracy of zonulin levels in distinguishing NCGS from IBS-D was 81%. After exclusion of CD, a diagnostic algorithm combining zonulin levels, symptoms and gender improved the accuracy to 89%.

CONCLUSION

Zonulin can be considered a diagnostic biomarker in NCGS and combined with demographic and clinical data differentiates NCGS from IBS-D with high accuracy. Wheat withdrawal was associated with a reduction in zonulin levels only in NCGS carrying HLA genotype.

Noninvasive Biomarkers of Gut Barrier Function in Patients Suffering from Diarrhea Predominant-IBS: An Update

The intestinal barrier plays a crucial role in the absorption of nutrients and in preventing the entry of pathogenic microorganisms and toxic molecules. Several studies have shown a compromised intestinal barrier associated with low-grade inflammation in the small intestinal mucosa in celiac disease, inflammatory bowel disease, and irritable bowel syndrome (IBS), particularly in IBS with diarrhea (IBS-D). In light of these new data, IBS is no longer considered a functional disease but rather a heterogeneous syndrome that has yet to be carefully studied. Therefore, investigating the integrity and function of the intestinal barrier is now essential to improving knowledge of the pathophysiology of IBS-D and to improving the management of IBS-D patients. However, the study of the intestinal barrier must clarify some still unsolved methodological aspects and propose standardised assays before becoming a useful diagnostic tool. In this framework, this review will discuss data about the tests that noninvasively evaluate the integrity and functionality of the human intestinal barrier, paying particular attention to patients with IBS-D, in both clinical and research situations.

TNF-α, IL-17, and IL-22 production in the rectal mucosa of nonceliac wheat sensitivity patients: role of adaptive immunity

In recent years, a new gluten- or wheat-related disease has emerged, a condition labeled "nonceliac gluten sensitivity" (NCGS) or "nonceliac wheat sensitivity" (NCWS). NCWS pathogenesis is still uncertain and attributed to very different mechanisms. We aimed to study the different T-lymphocyte subsets in the rectal mucosa of NCWS patients to demonstrate the possible contribution of adaptative immune response. Twelve patients (11 women, 1 man, age range 23-61 yr, median 32 yr) with a definitive diagnosis of NCWS were recruited at random for the present study. They underwent rectal endoscopy with multiple mucosal biopsies at the end of a double-blind placebo-controlled (DBPC) wheat challenge when they reported the reappearance of the symptoms. As controls we included 11 "healthy patients", sex- and age-matched with the patients who underwent colonoscopy evaluation for rectal bleeding due to hemorrhoids. Cells freshly obtained from rectal tissue were stained to detect anti-CD45, anti-CD3, anti-CD4, and anti-CD8. Furthermore, intracellular staining was performed with anti-tumor necrosis factor (TNF)-α, anti-interleukin (IL)-17, and anti-IL-22. Production of TNF-α by CD45+, CD3+, CD4+, and CD8+ cells, as well as of IL-17 by CD4+ cells, was higher in the rectal tissue of NCWS patients than in controls. On the contrary, IL-22 production by CD8+ cells was lower in NCWS patients than in the controls. In NCWS patients diagnosed by DBPC wheat challenge, there is a complex immunological activation, with a significant role for the adaptive response.NEW & NOTEWORTHY Nonceliac wheat sensitivity (NCWS) is a syndrome characterized by symptoms triggered by gluten intake. The pathogenesis is still uncertain. Studies have shown a role for innate immunity. We demonstrated that production of TNF-α by CD45+, CD3+, CD4+, and CD8+ cells and of IL-17 by CD4+ cells is higher in the rectal tissue of NCWS patients than in controls. We clearly demonstrated that in patients with NCWS there is a significant role for the adaptive response.

Brain fog and non-coeliac gluten sensitivity: Proof of concept brain MRI pilot study

AIMS

Non-Coeliac Gluten Sensitivity (NCGS) is poorly understood, particularly in terms of its neurological outcomes. We initially conducted a prospective postal survey to investigate its neurological presentation and symptom course. Results from this then motivated a follow-up pilot study utilising brain MRI to characterise potential diagnostic biomarkers for future research.

METHODS

Patients with NCGS were recruited from a specialist centre and completed a prospective postal questionnaire (N = 125). This summarised symptoms experienced, their severity and their course. Onset time was compared by Chi-squared analysis to data from the same centre concerning coeliac disease patients (N = 224). Five respondents on a strict gluten-free diet who self-reported brain fog then attended a pilot study, completing MR brain imaging/questionnaires before/after a gluten challenge. "Baseline" data were assessed for abnormalities, while symptom severity and cerebral blood flow (CBF) were compared before/after challenge.

RESULTS

Survey participants were aged 47 (85% female). Prevalence of neurological symptoms were: headaches (51%), brain fog (48%), balance issues (31%), tingling (19%). Median symptom resolution time was 48 hours, while onset was 90 minutes; onset pattern was not significantly different compared to CD patients (p = 0.322). Extra-intestinal symptoms worsened by 37%(±28) during a typical reaction. Predominantly non-statistical observations from the brain imaging study are discussed.

CONCLUSIONS

Neurological symptoms in NCGS are common, and onset time is comparable to that in CD. Brain imaging may be a useful future means of investigating physiological injury and responses to gluten in further study.

Celiac disease serology and gut microbiome following proton pump inhibitor treatment

BACKGROUND

Celiac disease is an autoimmune enteropathy characterized by an aberrant immune response to ingested gluten in genetically predisposed individuals. Studies have pointed to a rising prevalence of celiac disease in recent decades. Changes in diet and use of medication that may impact the gut microbiome have been suggested as potential contributors. Exposure to proton pump inhibitors (PPIs) was recently found to be associated with an increased risk for subsequent diagnosis of celiac disease. We aimed to investigate potential mechanisms for this link by examining the relationship between PPI use and gluten-related immune responses in the context of changes in gut microbiome.

METHODS

We performed a post hoc analysis of blood and fecal samples from a recent randomized trial in order to assess the potential association between PPI use and development of celiac disease serology in conjunction with alterations in gastrointestinal microbial composition. The study included 12 healthy participants who were administered a PPI (Omeprazole; 40 mg twice daily) for 4 or 8 weeks.

RESULTS

The analysis did not reveal an overall significant change in levels of serologic markers of celiac disease for the study cohort in response to PPI treatment. However, one individual developed a marked increase in the celiac disease-specific autoantibody response to transglutaminase 2 in conjunction with enhanced immune reactivity to gluten during the trial. Genotyping revealed positivity for the celiac disease-associated HLA-DQ2 and -DQ8 alleles. Furthermore, the observed elevation in antibody responses was closely associated with a sharp increase in fecal abundance of bacteria of the order Actinomycetales.

CONCLUSIONS

The results of this exploratory analysis support further investigation of molecular mechanisms involved in the contribution of PPIs to celiac disease risk through the potential enhancement of gluten immunopathology and changes in gut microbial population.

An updated overview of spectrum of gluten-related disorders: clinical and diagnostic aspects

The incidence of gluten-related disorders (GRDs) continues to increase and its global prevalence is estimated at approximately 5% of the population. Celiac disease (CD), dermatitis herpetiformis (DH), gluten ataxia (GA), wheat allergy (WA), and non-celiac gluten sensitivity (NCGS) are the five major GRDs that present with a wide range of clinical manifestations. The diagnosis of GRDs can be challenging because the typical and atypical clinical manifestations of the GRDs overlap. In this review, the current definitions of gluten-related disorders, focusing on their clinical features, diagnostic and therapeutic approaches are presented. We concluded that GRDs are usually diagnosed using a combination of clinical features, serological tests, and histopathological findings. Treatment usually involves dietary modification.

Nonceliac Gluten and Wheat Sensitivity

Non-celiac gluten and/or wheat sensitivity (NCGS) is thought to be an immune-mediated reaction to gluten or other components of wheat (eg, fructans or amylase trypsin inhibitors) with intestinal and extraintestinal symptoms which improve once gluten and/or wheat is eliminated from the diet and after a diagnosis of celiac disease and wheat allergy have been excluded with appropriate testing. However, there is a great deal of skepticism within the scientific community questioning the existence of NCGS as a distinct clinical disorder. There are no strict diagnostic criteria and a placebo-controlled rechallenge trial has been recommended for diagnosis. In research settings, a double-blind placebo-controlled rechallenge trial has been recommended for diagnosis. There are limited studies estimating the prevalence of NCGS using this study design. The existing studies have variable results likely due to the lack of a uniform diagnostic criterion, a great deal of dependence on the patient's perception of symptoms and a large nocebo effect in existing studies. In clinical practice, a single blind placebo-controlled rechallenge trial has been recommended for diagnosis. The pathogenesis of NCGS is unclear and there is no known biomarker or diagnostic histologic lesion for this condition. It is important to adopt a multidisciplinary team approach to patients with suspected NCGS with involvement of the primary care doctor, gastroenterologist, pathologist and nutritionist who may play an important role in diagnosis and treatment. There may especially be a role in elimination of food containing high quantity of both gluten and fructans. Furthermore, patients should be educated on the nutritional implications of consuming a long-term gluten-free diet.

Effect of Gluten-Free Diet on Gut Microbiota Composition in Patients with Celiac Disease and Non-Celiac Gluten/Wheat Sensitivity

Celiac disease (CD) and non-celiac gluten/wheat sensitivity (NCG/WS) are the two most frequent conditions belonging to gluten-related disorders (GRDs). Both these diseases are triggered and worsened by gluten proteins ingestion, although other components, such as amylase/trypsin inhibitors (ATI) and fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs), seem to be involved in the NCG/WS onset. Therefore, the only effective treatment to date is the long-life adherence to a strictly gluten-free diet. Recently, increasing attention has been paid to the intestinal barrier, a dynamic system comprising various components, which regulate the delicate crosstalk between metabolic, motor, neuroendocrine and immunological functions. Among the elements characterizing the intestinal barrier, the microbiota plays a key role, modulating the gut integrity maintenance, the immune response and the inflammation process, linked to the CD and NCG/WS outbreak. This narrative review addresses the most recent findings on the gut microbiota modulation induced by the gluten-free diet (GFD) in healthy, CD and NCG/WS patients.

Mast cell-nerve interactions correlate with bloating and abdominal pain severity in patients with non-celiac gluten / wheat sensitivity

BACKGROUND

Gastrointestinal (GI) and extra-GI symptoms/manifestations represent key clinical features of patients with non-celiac gluten/wheat sensitivity (NCG/WS). This study aimed to investigate neuro-immune (focusing on mast cells, MCs) interactions in the duodenal submucosa of patients with NCG/WS.

METHODS

Submucosal whole mounts from duodenal biopsies of 34 patients with self-reported NCG/WS, 28 with celiac disease (CD), 13 with functional dyspepsia (FD), and 24 healthy controls (HC) were analyzed by immunohistochemistry. Quantitative data on neuronal and MCs density and the percentage of MCs in close vicinity to nerves were obtained, and correlations among neurons, MC density and MC-nerve distance (D), and symptoms were assessed in the three groups.

KEY RESULTS

The number of submucosal neurons was not different among groups. In NCG/WS, MC density was not different from HC, while it was slightly increased vs. CD (P = .07) and significantly decreased vs. FD (P < .05). The percentage of MCs close to nerves (D < 15 µm) was similarly increased in all three pathological groups vs. HC (P < .001). In NCG/WS, MC infiltration correlated with bloating (P = .001) and abdominal pain severity (P = .03) and the percentage of MCs in proximity to neurons correlated with the number of GI symptoms (D < 5 µm; P = .05), bloating and abdominal pain severity (D < 15um; P = .01).

CONCLUSIONS AND INFERENCES

Submucosal MC infiltration and the close (within 15 µm) MC-to-nerve proximity in the duodenum of NCG/WS patients are features providing a histopathological basis to better understand GI symptoms in this condition.

Wheat Consumption Leads to Immune Activation and Symptom Worsening in Patients with Familial Mediterranean Fever: A Pilot Randomized Trial

We have identified a clinical association between self-reported non-celiac wheat sensitivity (NCWS) and Familial Mediterranean Fever (FMF). Objectives: A) To determine whether a 2-week double-blind placebo-controlled (DBPC) cross-over wheat vs. rice challenge exacerbates the clinical manifestations of FMF; B) to evaluate innate immune responses in NCWS/FMF patients challenged with wheat vs. rice. The study was conducted at the Department of Internal Medicine of the University Hospital of Palermo and the Hospital of Sciacca, Italy. Six female volunteers with FMF/NCWS (mean age 36 ± 6 years) were enrolled, 12 age-matched non-FMF, NCWS females, and 8 sex- and age-matched healthy subjects served as controls. We evaluated: 1. clinical symptoms by the FMF-specific AIDAI (Auto-Inflammatory Diseases Activity Index) score; 2. serum soluble CD14 (sCD14), C-reactive protein (CRP), and serum amyloid A (SSA); 3. circulating CD14+ monocytes expressing interleukin (IL)-1β and tumor necrosis factor (TNF)-α. The AIDAI score significantly increased in FMF patients during DBPC with wheat, but not with rice (19 ± 6.3 vs. 7 ± 1.6; p = 0.028). sCD14 values did not differ in FMF patients before and after the challenge, but were higher in FMF patients than in healthy controls (median values 11357 vs. 8710 pg/ml; p = 0.002). The percentage of circulating CD14+/IL-1β+ and of CD14+/TNF-α+ monocytes increased significantly after DBPC with wheat vs. baseline or rice challenge. Self-reported NCWS can hide an FMF diagnosis. Wheat ingestion exacerbated clinical and immunological features of FMF. Future studies performed on consecutive FMF patients recruited in centers for auto-inflammatory diseases will determine the real frequency and relevance of this association.

Exit Gluten-Free and Enter Low FODMAPs: A Novel Dietary Strategy to Reduce Gastrointestinal Symptoms in Athletes

Exercise-associated physiological disturbances alter gastrointestinal function and integrity. These alterations may increase susceptibility to dietary triggers, namely gluten and a family of short-chain carbohydrates known as FODMAPs (fermentable oligo-, di-, monosaccharides and polyols). A recent surge in the popularity of gluten-free diets (GFDs) among athletes without celiac disease has been exacerbated by unsubstantiated commercial health claims and high-profile athletes citing this diet to be the secret to their success. Up to 41% of athletes at least partially adhere to a GFD diet, with the belief that gluten avoidance improves exercise performance and parameters influencing performance, particularly gastrointestinal symptoms (GIS). In contrast to these beliefs, seminal work investigating the effects of a GFD in athletes without celiac disease has demonstrated no beneficial effect of a GFD versus a gluten-containing diet on performance, gastrointestinal health, inflammation, or perceptual wellbeing. Interestingly, the subsequent reduction in FODMAPs concurrent with the elimination of gluten-containing grains may actually be the factors affecting GIS improvement, not gluten. Pre-existent in the gastrointestinal tract or ingested during exercise, the osmotic and gas-producing effects of variably absorbed FODMAPs may trigger or increase the magnitude of exercise-associated GIS. Research using FODMAP reduction to address gastrointestinal issues in clinically healthy athletes is emerging as a promising strategy to reduce exercise-associated GIS. Applied research and practitioners merging clinical and sports nutrition methods will be essential for the effective use of a low FODMAP approach to tackle the multifactorial nature of gastrointestinal disturbances in athletes.

An Exploratory Gene Expression Study of the Intestinal Mucosa of Patients with Non-Celiac Wheat Sensitivity

Non-celiac wheat sensitivity (NCWS) is a recently recognized syndrome triggered by a gluten-containing diet. The pathophysiological mechanisms engaged in NCWS are poorly understood and, in the absence of laboratory markers, the diagnosis relies only on a double-blind protocol of symptoms evaluation during a gluten challenge. We aimed to shed light on the molecular mechanisms governing this disorder and identify biomarkers helpful to the diagnosis. By a genome-wide transcriptomic analysis, we investigated gene expression profiles of the intestinal mucosa of 12 NCWS patients, as well as 7 controls. We identified 300 RNA transcripts whose expression differed between NCWS patients and controls. Only 37% of these transcripts were protein-coding RNA, whereas the remaining were non-coding RNA. Principal component analysis (PCA) and receiver operating characteristic curves showed that these microarray data are potentially useful to set apart NCWS from controls. Literature and network analyses indicated a possible implication/dysregulation of innate immune response, hedgehog pathway, and circadian rhythm in NCWS. This exploratory study indicates that NCWS can be genetically defined and gene expression profiling might be a suitable tool to support the diagnosis. The dysregulated genes suggest that NCWS may result from a deranged immune response. Furthermore, non-coding RNA might play an important role in the pathogenesis of NCWS.

Pathogenesis of Celiac Disease and Other Gluten Related Disorders in Wheat and Strategies for Mitigating Them

Wheat is a major cereal crop providing energy and nutrients to the billions of people around the world. Gluten is a structural protein in wheat, that is necessary for its dough making properties, but it is responsible for imparting certain intolerances among some individuals, which are part of this review. Most important among these intolerances is celiac disease, that is gluten triggered T-cell mediated autoimmune enteropathy and results in villous atrophy, inflammation and damage to intestinal lining in genetically liable individuals containing human leukocyte antigen DQ2/DQ8 molecules on antigen presenting cells. Celiac disease occurs due to presence of celiac disease eliciting epitopes in gluten, particularly highly immunogenic alpha-gliadins. Another gluten related disorder is non-celiac gluten-sensitivity in which innate immune-response occurs in patients along with gastrointestinal and non-gastrointestinal symptoms, that disappear upon removal of gluten from the diet. In wheat allergy, either IgE or non-IgE mediated immune response occurs in individuals after inhalation or ingestion of wheat. Following a life-long gluten-free diet by celiac disease and non-celiac gluten-sensitivity patients is very challenging as none of wheat cultivar or related species stands safe for consumption. Hence, different molecular biology, genetic engineering, breeding, microbial, enzymatic, and chemical strategies have been worked upon to reduce the celiac disease epitopes and the gluten content in wheat. Currently, only 8.4% of total population is affected by wheat-related issues, while rest of population remains safe and should not remove wheat from the diet, based on false media coverage.

A Comparative Study of Modern and Heirloom Wheat on Indicators of Gastrointestinal Health

Wheat consumption has declined amid growing concerns about gluten-sensitivity. To determine if genetic manipulation of wheat contributes to systemic and localized gut inflammation, we compared the effects of the modern variety Gallagher and a blend of two heirloom varieties, Turkey and Kharkof, on measures of gut inflammation, structural characteristics, and barrier integrity under normal and Western diet (WD) conditions in C57BL/6 mice. Indicators of gut inflammation, including lymphocyte infiltration and cytokine expression, were largely unaffected by WD or wheat, although WD elevated interferon-γ (Ifng) and heirloom varieties modestly reduced interleukin-17 (Il17) in the context of WD. WD negatively affected jejunal villi structure, while the modern variety improved villi structure in the ileum. Relative mRNA and tight junction proteins and serum lipopolysaccharide binding protein were unaltered by WD or wheat. These findings indicate that the modern variety did not compromise barrier function or contribute to gut inflammation compared to its heirloom predecessor.

An explorative study identifies miRNA signatures for the diagnosis of non-celiac wheat sensitivity

Non-celiac wheat sensitivity (NCWS), also referred to as non-celiac gluten sensitivity, is a recently described disorder triggered by wheat/gluten ingestion. NCWS elicits a wide range of symptoms including diarrhoea, intestinal discomfort, and fatigue in analogy with other wheat/gluten-related disorders and celiac disease in particular. From the pathological standpoint, NCWS patients only have a slight increase of intraepithelial lymphocytes, while antibodies to tissue transglutaminase (tTG) and villous atrophy, otherwise diagnostic features of celiac disease, are absent. To date, the diagnosis of NCWS relies on symptoms and exclusion of confounding diseases, since biomarkers are not yet available. Here, the expression levels of selected miRNAs were examined in duodenal biopsies and peripheral blood leukocytes collected from newly diagnosed patients with NCWS and, as controls, from patients with celiac disease and gluten-independent gastrointestinal problems. We identified a few miRNAs whose expression is higher in the intestinal mucosa of patients affected by NCWS in comparison to control patients affect by gluten-independent dyspeptic symptoms (Helicobacter pylori-negative) and celiac disease. The present study provided the first evidence that NCWS patients have a characteristic miRNA expression patterns, such peculiarity could be exploited as a biomarker to the diagnosis of this disease.

Food additives: Assessing the impact of exposure to permitted emulsifiers on bowel and metabolic health - introducing the FADiets study

Emulsifiers are common components of processed foods consumed as part of a Western diet. Emerging in vitro cell-line culture, mouse model and human intestinal tissue explant studies have all suggested that very low concentrations of the food emulsifier polysorbate 80 may cause bacterial translocation across the intestinal epithelium, intestinal inflammation and metabolic syndrome. This raises the possibility that dietary emulsifiers might be factors in conditions such as coronary artery disease, type 2 diabetes and Crohn's disease. The potential mechanism behind the observed effects of this emulsifier is uncertain but may be mediated via changes in the gut microbiota or by increased bacterial translocation, or both. It is also unknown whether these effects are generalisable across all emulsifiers and detergents, including perhaps the natural emulsifier lecithin or even conjugated bile acids, particularly if the latter escape reabsorption and pass through to the distal ileum or colon. A major objective of the Medical Research Council (MRC)-funded Mechanistic Nutrition in Health (MECNUT) Emulsifier project is therefore to investigate the underlying mechanisms and effects of a range of synthetic and natural emulsifiers and detergents in vitro and in vivo, and to determine the effects of a commonly consumed emulsifier (soya lecithin) on gut and metabolic health through a controlled dietary intervention study in healthy human volunteers - the FADiets study. This report provides an overview of the relevant literature, discussing the impact of emulsifiers and other additives on intestinal and metabolic health, and gives an overview of the studies being undertaken as part of the MECNUT Emulsifier project.

Intestinal Barrier Function in Gluten-Related Disorders

Gluten-related disorders include distinct disease entities, namely celiac disease, wheat-associated allergy and non-celiac gluten/wheat sensitivity. Despite having in common the contact of the gastrointestinal mucosa with components of wheat and other cereals as a causative factor, these clinical entities have distinct pathophysiological pathways. In celiac disease, a T-cell mediate immune reaction triggered by gluten ingestion is central in the pathogenesis of the enteropathy, while wheat allergy develops as a rapid immunoglobulin E- or non-immunoglobulin E-mediated immune response. In non-celiac wheat sensitivity, classical adaptive immune responses are not involved. Instead, recent research has revealed that an innate immune response to a yet-to-be-defined antigen, as well as the gut microbiota, are pivotal in the development in this disorder. Although impairment of the epithelial barrier has been described in all three clinical conditions, its role as a potential pathogenetic co-factor, specifically in celiac disease and non-celiac wheat sensitivity, is still a matter of investigation. This article gives a short overview of the mucosal barrier of the small intestine, summarizes the aspects of barrier dysfunction observed in all three gluten-related disorders and reviews literature data in favor of a primary involvement of the epithelial barrier in the development of celiac disease and non-celiac wheat sensitivity.

Microbiota: a novel regulator of pain

Among the various regulators of the nervous system, the gut microbiota has been recently described to have the potential to modulate neuronal cells activation. While bacteria-derived products can induce aversive responses and influence pain perception, recent work suggests that "abnormal" microbiota is associated with neurological diseases such as Alzheimer's, Parkinson's disease or autism spectrum disorder (ASD). Here we review how the gut microbiota modulates afferent sensory neurons function and pain, highlighting the role of the microbiota/gut/brain axis in the control of behaviors and neurological diseases. We outline the changes in gut microbiota, known as dysbiosis, and their influence on painful gastrointestinal disorders. Furthermore, both direct host/microbiota interaction that implicates activation of "pain-sensing" neurons by metabolites, or indirect communication via immune activation is discussed. Finally, treatment options targeting the gut microbiota, including pre- or probiotics, will be proposed. Further studies on microbiota/nervous system interaction should lead to the identification of novel microbial ligands and host receptor-targeted drugs, which could ultimately improve chronic pain management and well-being.

The 5 Ws of a gluten challenge for gluten-related disorders

Gluten-related disorders (GRDs) are gradually emerging as epidemiologically relevant diseases, with a global prevalence estimated to be approximately 5% in the population. Conditions related to gluten ingestion include celiac disease (CD), wheat allergy (WA), and nonceliac gluten sensitivity (NCGS). Although mediated by different pathogenic pathways, these 3 conditions share similar clinical manifestations and can present a difficult differential diagnosis. The gluten challenge (GC) is an important diagnostic tool for GRDs, but there is great variability in regards to deciding which patients should be challenged, what amount of gluten should be used, what the GC duration should be, when and where the GC should occur, and, sometimes, why to conduct a GC. This review summarizes the current knowledge about the desirable characteristics of GCs in the 3 main GRDs following a 5 Ws approach-that is, the 5 main journalistic questions: who, what, when, where, why. The answers will help to determine the correct use of the GC in diagnosing GRDs.

Celiac Disease: Updates on Pathology and Differential Diagnosis

Celiac disease is a gluten-triggered immune-mediated disorder, characterized by inflammation of the enteric mucosa following lymphocytic infiltration and eventually resulting in villous blunting. There have been many developments in refining diagnostic laboratory tests for celiac disease in the last decade. Biopsy-sparing diagnostic guidelines have been proposed and validated in a few recent prospective studies. However, despite these developments, histologic evaluation of duodenal mucosa remains one of the most essential diagnostic tools as it helps in the diagnosis of celiac disease in individuals who do not fulfill the biopsy-sparing diagnostic criteria and in those not responding to a gluten-free diet. Histologic evaluation also allows for the assessment of mucosal recovery after treatment and in the identification of concurrent intestinal diseases. Therefore, pathologists should be familiar with the histologic spectrum of celiac disease and need to be aware of other disorders with similar symptoms and histopathology that may mimic celiac disease. This review aims to provide pathologists with updates on celiac laboratory testing, biopsy-sparing diagnostic criteria, histopathology, complications, and differential diagnoses of celiac disease.

Targeting the gut-skin axis-Probiotics as new tools for skin disorder management?

The existence of a gut-skin axis is supported by increasing evidence, but its translational potential is not widely recognized. Studies linked inflammatory skin diseases to an imbalanced gut microbiome; hence, the modulation of the gut microbiota to improve skin condition seems to be a feasible approach. Today, there is a growing interest in natural products as alternatives to synthetic drugs. In this respect, oral probiotics could be a simple, safe and cheap modality in the therapeutic management of skin inflammation. Unfortunately, very few studies have looked into how probiotic supplementation influences inflammatory skin disorders. The result, though promising, are difficult to implement in clinical practice due to the heterogeneity of the applied supplemental regimen in the different studies. In this Viewpoint, we aim to encourage the conduction of more research in that direction to explore unambiguously the therapeutic potential of oral probiotics in dermatology. We focus on the most common inflammatory skin diseases (atopic dermatitis, psoriasis, rosacea, acne vulgaris) with an associated gut dysbiosis, but we also discuss some less common, but very serious skin pathologies (eg erythema nodosum, pyoderma gangrenosum, hidradenitis suppurativa) that are possibly linked to a disturbed gut flora composition. We dissect the possible mechanisms along the gut-skin axis and highlight novel points where probiotics could interfere in this communication in the diseased state.

Food Intolerances

Food intolerances are estimated to affect up to 20% of the population but complete understanding of diagnosis and management is complicated, given presentation and non-immunological mechanisms associated vary greatly. This review aims to provide a scientific update on common food intolerances resulting in gastrointestinal and/or extra-intestinal symptoms. FODMAP sensitivity has strong evidence supporting its mechanisms of increased osmotic activity and fermentation with the resulting distention leading to symptoms in those with visceral hypersensitivity. For many of the other food intolerances reviewed including non-coeliac gluten/wheat sensitivity, food additives and bioactive food chemicals, the findings show that there is a shortage of reproducible well-designed double-blind, placebo-controlled studies, making understanding of the mechanisms, diagnosis and management difficult. Enzyme deficiencies have been proposed to result in other food sensitivities including low amine oxidase activity resulting in histamine intolerance and sucrase-isomaltase deficiency resulting in reduced tolerance to sugars and starch. Lack of reliable diagnostic biomarkers for all food intolerances result in an inability to target specific foods in the individual. As such, a trial-and-error approach is used, whereby suspected food constituents are reduced for a short-period and then re-challenged to assess response. Future studies should aim to identify biomarkers to predict response to dietary therapies.

Adverse Reactions to Wheat or Wheat Components

Wheat is an important staple food globally, providing a significant contribution to daily energy, fiber, and micronutrient intake. Observational evidence for health impacts of consuming more whole grains, among which wheat is a major contributor, points to significant risk reduction for diabetes, cardiovascular disease, and colon cancer. However, specific wheat components may also elicit adverse physical reactions in susceptible individuals such as celiac disease (CD) and wheat allergy (WA). Recently, broad coverage in the popular and social media has suggested that wheat consumption leads to a wide range of adverse health effects. This has motivated many consumers to avoid or reduce their consumption of foods that contain wheat/gluten, despite the absence of diagnosed CD or WA, raising questions about underlying mechanisms and possible nocebo effects. However, recent studies did show that some individuals may suffer from adverse reactions in absence of CD and WA. This condition is called non-celiac gluten sensitivity (NCGS) or non-celiac wheat sensitivity (NCWS). In addition to gluten, wheat and derived products contain many other components which may trigger symptoms, including inhibitors of α-amylase and trypsin (ATIs), lectins, and rapidly fermentable carbohydrates (FODMAPs). Furthermore, the way in which foods are being processed, such as the use of yeast or sourdough fermentation, fermentation time and baking conditions, may also affect the presence and bioactivity of these components. The present review systematically describes the characteristics of wheat-related intolerances, including their etiology, prevalence, the components responsible, diagnosis, and strategies to reduce adverse reactions.

Going Against the Grains: Gluten-Free Diets in Patients Without Celiac Disease-Worthwhile or Not?

While the gluten-free diet (GFD) is the only known effective therapy for celiac disease, in recent years it has become increasingly popular in the USA and worldwide, with many believing it to be more "healthful" and others claiming that it has beneficial effects for health conditions, many extraintestinal, other than celiac disease. This review examines the evidence for use of the GFD in patients without celiac disease who self-report intestinal and/or extraintestinal symptoms (non-celiac gluten sensitivity), as well as for enhancement of athletic performance and treatment of autism, rheumatoid arthritis, and psychiatric disorders. Overall, the evidence for use of GFDs in conditions other than celiac disease is poor. Though non-celiac gluten sensitivity may ultimately emerge as a biomarker-defined condition, a large proportion of patients with apparent non-celiac gluten sensitivity have, after careful investigation, an alternative diagnosis. In light of this, and coupled with the potential physical and psychological harms associated with the avoidance of gluten, initiating a GFD should not be encouraged for people who have these other conditions or are seeking physical/athletic enhancement.

A Population Survey of Dietary Attitudes towards Gluten

It is unclear how the prevalence of people who believe the gluten-free diet (GFD) to be generally healthy (“Lifestylers”) is impacting the overall rates of self-reported gluten sensitivity (GS). We repeated a population survey from 2012 in order to examine how attitudes towards GS have changed over time. Our survey (N = 1004) was administered in Sheffield (UK) in 2015, replicating the 2012 experiment. The questionnaire included a food frequency survey and assessed self-reported GS as well as associated variables (prevalence, current diet, pre-existing conditions, etc.). The overall rates of key variables and chi-squared analysis in comparison to the previous survey were as follows: self-reported GS was 32.8% (previously 12.9%, p < 0.001), pre-existing coeliac disease (CD) was 1.2% (previously 0.8%, p = 0.370), following a GFD was 3.7% (previously 3.7%, p = 0.997). Self-reported GS was positively associated with some pre-existing conditions, including anxiety, depression, chronic fatigue, headaches, and other food allergies/intolerances (including irritable bowel syndrome (IBS); chi-squared analyses, all p < 0.001). Over a 3-year period, the fraction of people who self-reported GS increased by over 250%. Despite this, arguably more meaningful indications of underlying physiological GS remained comparable. This research suggests that the public perception of gluten is causing a marked increase in the number of people who erroneously believe they are sensitive to it.

Lactobacilli Degrade Wheat Amylase Trypsin Inhibitors to Reduce Intestinal Dysfunction Induced by Immunogenic Wheat Proteins

BACKGROUND & AIMS

Wheat-related disorders, a spectrum of conditions induced by the ingestion of gluten-containing cereals, have been increasing in prevalence. Patients with celiac disease have gluten-specific immune responses, but the contribution of non-gluten proteins to symptoms in patients with celiac disease or other wheat-related disorders is controversial.

METHODS

C57BL/6 (control), Myd88^-/-, Ticam1^-/-, and Il15^-/- mice were placed on diets that lacked wheat or gluten, with or without wheat amylase trypsin inhibitors (ATIs), for 1 week. Small intestine tissues were collected and intestinal intraepithelial lymphocytes (IELs) were measured; we also investigated gut permeability and intestinal transit. Control mice fed ATIs for 1 week were gavaged daily with Lactobacillus strains that had high or low ATI-degrading capacity. Nonobese diabetic/DQ8 mice were sensitized to gluten and fed an ATI diet, a gluten-containing diet or a diet with ATIs and gluten for 2 weeks. Mice were also treated with Lactobacillus strains that had high or low ATI-degrading capacity. Intestinal tissues were collected and IELs, gene expression, gut permeability and intestinal microbiota profiles were measured.

RESULTS

In intestinal tissues from control mice, ATIs induced an innate immune response by activation of Toll-like receptor 4 signaling to MD2 and CD14, and caused barrier dysfunction in the absence of mucosal damage. Administration of ATIs to gluten-sensitized mice expressing HLA-DQ8 increased intestinal inflammation in response to gluten in the diet. We found ATIs to be degraded by Lactobacillus, which reduced the inflammatory effects of ATIs.

CONCLUSIONS

ATIs mediate wheat-induced intestinal dysfunction in wild-type mice and exacerbate inflammation to gluten in susceptible mice. Microbiome-modulating strategies, such as administration of bacteria with ATI-degrading capacity, may be effective in patients with wheat-sensitive disorders.

Elimination of Omega-1,2 Gliadins From Bread Wheat (Triticum aestivum) Flour: Effects on Immunogenic Potential and End-Use Quality

The omega-1,2 gliadins are a group of wheat gluten proteins that contain immunodominant epitopes for celiac disease (CD) and also have been associated with food allergies. To reduce the levels of these proteins in the flour, bread wheat (Triticum aestivum cv. Butte 86) was genetically transformed with an RNA interference plasmid that targeted a 141 bp region at the 5' end of an omega-1,2 gliadin gene. Flour proteins from two transgenic lines were analyzed in detail by quantitative two-dimensional gel electrophoresis and tandem mass spectrometry. In one line, the omega-1,2 gliadins were missing with few other changes in the proteome. In the other line, striking changes in the proteome were observed and nearly all gliadins and low molecular weight glutenin subunits (LMW-GS) were absent. High molecular weight glutenin subunits (HMW-GS) increased in this line and those that showed the largest increases had molecular weights slightly less than those in the non-transgenic, possibly due to post-translational processing. In addition, there were increases in non-gluten proteins such as triticins, purinins, globulins, serpins, and alpha-amylase/protease inhibitors. Reactivity of flour proteins with serum IgG and IgA antibodies from a cohort of CD patients was reduced significantly in both transgenic lines. Both mixing time and tolerance were improved in the line without omega-1,2 gliadins while mixing properties were diminished in the line missing most gluten proteins. The data suggest that biotechnology approaches may be used to create wheat lines with reduced immunogenic potential in the context of gluten sensitivity without compromising end-use quality.

The overlap of irritable bowel syndrome and noncoeliac gluten sensitivity

PURPOSE OF REVIEW

There has been significant interest in gluten over the last decade, with an increase in interest of gluten-related disorders outside coeliac disease. Particularly, there has been a focus on the role of gluten in noncoeliac gluten sensitivity (NCGS) and irritable bowel syndrome (IBS). There is significant overlap between both of these conditions, with the aim of this review to explore their complex relationship.

RECENT FINDINGS

Gluten has been demonstrated to generate symptoms in individuals with NCGS. However, there appears to be an increasing role for gluten in symptom generation in patients with IBS also. Other components of wheat, other than gluten, are now also thought to be contributing factors in symptom generation.

SUMMARY

There appears to be significant overlap between IBS and NCGS. It is likely that a subset of patients presenting with IBS actually have NCGS. In addition, it is likely that individuals with IBS may also have symptoms triggered by gluten. With the pathophysiology of both conditions not fully understood, as well as increasing knowledge of wheat components in symptom generation, further research is required to help distinguish between both.

Coordinated Induction of Antimicrobial Response Factors in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by dysregulated autoantibody production and complement activation leading to multi-organ damage. The disease is associated with increased intestinal permeability. In this study, we tested the hypothesis that SLE subjects have increased systemic exposure to bacteria. Since bacteria induce the expression of antimicrobial response factors (ARFs), we measured the levels of a series of clinically relevant ARFs in the plasma of SLE subjects. We found that levels of sCD14, lysozyme, and CXCL16 were significantly elevated in SLE subjects. A strong positive correlation was also observed between sCD14 and SELENA-SLEDAI score. Interestingly, the ratio of EndoCAb IgM:total IgM was significantly decreased in SLE and this ratio was negatively correlated with sCD14 levels. Although, there were no significant differences in the levels of lipopolysaccharide binding protein (LBP) and fatty acid binding protein 2 (FABP2), we observed significant positive correlations between lysozyme levels and sCD14, LBP, and FABP2. Moreover, galectin-3 levels also positively correlate with lysozyme, sCD14, and LBP. Since our SLE cohort comprised 43.33% males, we were able to identify gender-specific changes in the levels of ARFs. Overall, these changes in the levels and relationships between ARFs link microbial exposure and SLE. Approaches to reduce microbial exposure or to improve barrier function may provide therapeutic strategies for SLE patients.

The gut microbiota promotes the pathogenesis of schizophrenia via multiple pathways

Schizophrenia is a severe mental disorder with unknown etiology. Many mechanisms, including dysregulation of neurotransmitters, immune disturbance, and abnormal neurodevelopment, are proposed for the pathogenesis of schizophrenia. The significance of communication between intestinal flora and the central nervous system through the gut-brain axis is increasingly being recognized. The intestinal microbiota plays an important role in regulating neurotransmission, immune homeostasis, and brain development. We hypothesize that an imbalance in intestinal flora causes immune activation and dysfunction in the gut-brain axis, contributing to schizophrenia. In this review, we examine recent studies that explore the intestinal flora and immune-mediated neurodevelopment of schizophrenia. We conclude that an imbalance in intestinal flora may reduce protectants and increase neurotoxin and inflammatory mediators, causing neuronal and synaptic damage, which induces schizophrenia.

IRRITABLE BOWEL SYNDROME, FOOD INTOLERANCE AND NON- CELIAC GLUTEN SENSITIVITY. A NEW CLINICAL CHALLENGE

Approximately 80% of irritable bowel syndrome (IBS) patients report that their symptoms are triggered after ingesting one or specific food groups. Gluten, wheat and related proteins (e.g., amylase-trypsin inhibitors, and fermentable oligo-di-mono-saccharides and polyols (FODMAPs) are the most relevant IBS symptom triggers, although the true 'culprit(s)' is/are still not well established. The concept of causal relationship between gluten intake and the occurrence of symptoms in the absence of celiac disease and wheat allergy was termed non-celiac gluten sensitivity (NCGS). The borderline between celiac disease, wheat allergy, IBS and NCGS is not always clearly distinguishable, and the frequency and clinical identity of NGCS are still unclear. An overlap between IBS and NCGS has been detected. The incomplete knowledge of the etiopathogenesis of these clinical conditions, lack of data on their real epidemiology, as well as the absence of a gold standard for their diagnosis, make the overall picture difficult to understand "It is crucial to well define the interaction between IBS, food intolerance and NGCS, since the role of diet in IBS and its dietary management is an essential tool in the treatment of a large number of these patients". The objective of the present review is to provide an overview highlighting the interaction between IBS, food intolerance and NCGS in order to unravel whether gluten/wheat/FODMAP sensitivity represents 'facts' and not 'fiction' in IBS symptoms.